Three-dimensional fiber networks are known. These are generally derived from textile fabrics that have been impregnated with a thermoset polymer or a low melting thermoplastic and then molded into the desired shape. For example, U.S. Pat. No. 4,631,221 describes a laminate containing a rigid three-dimensional fiber network having regularly arranged projections. The three-dimensional network is placed between two sheets of rigid material. The three-dimensional network used in the laminate is made by the deep-drawing of a sheet-like textile fabric to make projections. The textile fabric was previously impregnated with a thermoset resin and dried to yield a pre-preg, and is cured after deep-drawing. The textile fabric is made from a multifilament yarn so that a larger amount of resin can be absorbed in the interfilament regions. U.S. Pat. No. 5,364,686 describes a three-dimensional shaped material which is made from a fabric comprising a yarn that has thermoplastic fibers mixed with higher melting reinforcing fibers; the fabric is shaped by deep drawing at a temperature high enough to melt the lower melting thermoplastic material but not the reinforcing fiber to yield a three-dimensional structure which becomes rigid after it is cooled, possibly due to the fixing of fiber crossover points. Finally, U.S. Pat. No. 4,890,877 describes an energy absorbing structure for use in automobile doors, wherein the energy absorbing structure is a highly stretchable lightweight material that has been coated with a resin (e.g. a thermoset) and then molded so that it has a series of projections, which are preferably truncated cones. The structure after molding does not appear to have an open fiber network appearance.
The fiber network structures described above and elsewhere generally are rigid and are intended for use mainly as lightweight structural materials.